Mode of action

Microbiostatic activity inhibits the reproduction of microorganisms. The cells are not killed, but their growth is suppressed. 

Microbicidal activity kills the bacteria or fungi. It reduces the number of microorganisms. 

Depending on the target organisms, the term microbiostatic is replaced by bacteriostatic, or fungistatic, for the first activity. The activity is named bactericidal or fungicidal for the second case. In some cases, for example, the same antimicrobial substance can act as both as microbicidal and microbiostatic agent. The mode of activity 

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This chapter is divided in two parts additives for motor fuels and additives for lubricants. Concerning additives for gasoline, one will find here in Chapter 9 some useful complements to Chapter 5, especially regarding the synthesis of additives and their modes of action. 

One can distinguish three important additive classes according to their modes of action ... 

ELECTRAS - web-based data analysis system. The software supports 2x2 different modes of action the modes for expert and novice engineers and the modes for expert and novice computational chemists. htip //www2.chemie.uni-erlangen.de/projects/eDAS/index.himl... 

Figure 10.1-S. LCsq values for the fish species Pimephalas promelas versus log P of a highly diverse set of organic chemicals. Chemicals are marked by their mode of action.

Tutorial Classifying Compounds into Different Modes of Action... 

The resulting distribution of compounds having different modes of action in the output layer after training the network is shown in figure 10.1-10. 

Figure 10.1-10. Distribution of the coinpounds in the output layer according to modes of action (most frequent MOA shown),...

Figure 10.1-11. Architecture of the counterpropagation network for the classification of toxicants with nine output layers, one for each mode of action.

In polymers such as polystyrene that do not readily undergo charring, phosphoms-based flame retardants tend to be less effective, and such polymers are often flame retarded by antimony—halogen combinations (see Styrene). However, even in such noncharring polymers, phosphoms additives exhibit some activity that suggests at least one other mode of action. Phosphoms compounds may produce a barrier layer of polyphosphoric acid on the burning polymer (4,5). Phosphoms-based flame retardants are more effective in styrenic polymers blended with a char-forming polymer such as polyphenylene oxide or polycarbonate. 

Phosphoms-containing additives can act in some cases by catalyzing thermal breakdown of the polymer melt, reducing viscosity and favoring the flow or drip of molten polymer from the combustion zone (25). On the other hand, red phosphoms [7723-14-0] has been shown to retard the nonoxidative pyrolysis of polyethylene (a radical scission). For that reason, the scavenging of radicals in the condensed phase has been proposed as one of several modes of action of red phosphoms (26). 

Vapor-Phase Mechanisms. Phosphoms flame retardants can also exert vapor-phase flame-retardant action. Trimethyl phosphate [512-56-1] C H O P, retards the velocity of a methane—oxygen flame with about the same molar efficiency as antimony trichloride (30,31). Both physical and chemical vapor-phase mechanisms have been proposed for the flame-retardant action of certain phosphoms compounds. Physical (endothermic) modes of action have been shown to be of dominant importance in the flame-retardant action of a wide range of non-phosphoms-containing volatile compounds (32). 

Many plant substances possess antivitamin D activity but the mode of action and in most cases the identity remain unknown. Rachitogenic factors have been observed in yeast. Because of the metaboHc interrelationships that exist between vitamin D, Ca, and P, it is sometimes difficult to differentiate between chelators of mineral elements and tme antivitamins. One reported vitamin D antagonist in oats was later identified as phytic acid (72). 

Intoxication by aflatoxkis is referred to as aflatoxicosis. Edema and necrosis of hepatic and renal tissues seem characteristic of aflatoxicosis, and hemorrhagic enteritis accompanied by nervous symptoms often appear ki experimental animals. The mode of action of aflatoxkis kivolve an kiteraction with DNA and inhibition of the polymerases responsible for DNA and RNA synthesis (96). 

He/minthosporium (15). The mode of action is considered to be inhibition of the enzyme NADPH-cytochrome C reductase, which results in the generation of free radicals and/or peroxide derivatives of flavin which oxidize adjacent unsaturated fatty acids to dismpt membrane integrity (16) (see Enzyme inhibitors). 

Transgenic soybean plants expressing the CTP-CP4 EPSPS display commercial levels of Roundup tolerance. These results vaUdate the importance of substrate kinetics of EPSPS in order to maintain adequate rates of aromatic biosynthesis. Furthermore, the fact that glyphosate tolerance can be obtained by expression of a glyphosate-tolerant EPSPS illustrates that the herbicidal mode of action of glyphosate is related solely to inhibition of the EPSPS reaction. 

Mechanism of Action. The mechanisms by which antibiotic adrninistration at subtherapeutic levels enhance growth rate and efficiency of gain in growing animals have not been clarified. Possible modes of action include disease control, nutrient sparing, and metaboHc effects. There is extensive evidence that the principal benefit from subtherapeutic use of antibiotics results from the control of harmfiil microorganisms. 

The nutrient sparing effect of antibiotics may result from reduction or elimination of bacteria competing for consumed and available nutrients. It is also recognized that certain bacteria synthesize vitamins (qv), amino acids (qv), or proteins that may be utilized by the host animal. Support of this mode of action is found in the observed nutritional interactions with subtherapeutic use of antibiotics in animal feeds. Protein concentration and digestibiHty, and amino acid composition of consumed proteins may all influence the magnitude of response to feeding antibiotics. Positive effects appear to be largest... 

The mode of action is by inhibiting 5-enolpymvyl-shikimate-3-phosphate synthase. Roundup shuts down the production of the aromatic amino acids phenylalanine, tyrosine, and tryptophane (30). Whereas all these amino acids are essential to the survival of the plant, tryptophane is especially important because it is the progenitor for indole-3-acetic acid, or auxin, which plays an important role in growth and development, and controls cell extension and organogenesis. 

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